Unitary work changer for a machining center

ABSTRACT

This invention relates to a greatly simplified workpiece changer mechanism in combination with a simplified tool storage and changing mechanism for a machine tool. To accomplish this, a rotatable work carrying spindle is adapted to support a workpiece for selective rectilinear movement relative to an associated rotary cutting tool, and to support the same workpiece for selective rotational movement relative to a rectilinearly movable cutting tool carried by the same spindle. The work receiving spindle is mounted in spaced apart relationship to a storage support adapted to releasably carry a workpiece for selective interchange with a workpiece carried by the work spindle. To effect a selective interchange of workpieces between the work spindle and the storage support, a work transfer arm is pivotally supported between the work spindle and the work support. At its opposite ends, the work transfer arm is provided with oppositely extending openings respectively adapted to receive work support rings of like size and configuration. The arrangement is such that the transfer arm pivots 90° in one direction for moving the oppositely disposed openings presented thereby into clamping engagement with the workpieces respectively carried by the work spindle and the storage member. Automatic clamping means respectively associated with the work receiving openings are disposed to be actuated into clamped engagement with the workpieces for retaining them in predetermined angularly clamped positions during the interchange. Next, the work spindle and support member are retracted from engagement with the respective work supports, and the transfer arm rotated through another 180° for respectively realigning the work supports in interchanged position with the work spindle and the support member respectively. The latter are moved forward into clamping reengagement with the now interchanged work supports. The transfer arm clamping means are then released and the transfer arm pivotally moved 90° in the opposite direction to return the transfer arm to its central parked position. To accelerate controlled movement of the work transfer arm, a velocity control system is provided in combination with automatic clamping means for retaining work support rings in clamped engagement within the oppositely disposed openings provided in the transfer member.

This application is a division of pending application Ser. No. 311,851,filed Dec. 4, 1972, now U.S. Pat. No. 4,013,176, which, in turn, is acontinuation of application Ser. No. 12,057, filed Feb. 17, 1970 andsubsequently abandoned.

BACKGROUND OF THE INVENTION

The present invention can be classified generally with the group ofprior devices identified as machining centers. As presently known, amachining center comprises a machine having the capability of bringing aplurality of different metal cutting tools to a workpiece in selectedsequence for performing a sequence of different metal cutting operationsupon that workpiece. The present machine belongs to a new and novelgroup of machines having a tool spindle or tool support adapted tosupport a rotatable metal cutting tool for rotational movement, or tosupport a non-rotatable cutting tool for rectilinear movement to performa metal cutting operation. During rotational movement, the rotarycutting tool is moved relative to a workpiece carried for rectilinearmovement to perform one type of metal cutting operation, either millingor drilling. During nonrotational, rectilinear movement, a nonrotatablecutting tool is carried by the same tool spindle for cutting movementrelative to the same workpiece now carried for relative rotationalmovement to perform a different type of metal cutting operation. Inother words, the spindle is selectively rotated for moving a cuttingtool relative to a rectilinearly movable work support; and, the toolspindle is rectilinearly moved relative to the same workpiece carriedfor relative rotational movement to perform a lathe type metal cuttingoperation.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a work spindle selectively adapted tosupport a workpiece for rotation, or for rectilinear movement. Toaccomplish this, the work spindle is adapted to releasably and fixedlyengage a work securing ring. As the work spindle is power driven forrotating a workpiece or moving a workpiece along a rectilinear pathrelative to a cutting tool carried by a cooperatively movable toolspindle, a next workpiece to be machined is loaded into a spaced apartstorage support member. The next work support is secured within a likestorage ring which is releasably clamped within the storage supportmember. A mechanical workpiece changer is operative to remove thefixture ring with the workpiece secured thereon at the change positionas a unit from the storage member, and transfer the complete fixturering and workpiece as a unit to the workpiece spindle. At the same time,the workpiece changer is operative to remove and transfer a fixture ringwith a workpiece secured thereto which has had a machining operationperformed thereon from the work spindle and transfer that complete unitto the support member for subsequent removal from the machine. Duringtransfer movement, the workpiece changer is adapted to retain theworkpiece fixture rings in angularly clamped positions. The nextworkpiece transferred into the work spindle will have a machiningoperation or series of machining operations performed on it, and duringthe machining operation, the previously finished workpiece may beremoved from the associated fixture ring and a new workpiece secured tothat support ring. To perform the required machining operations on aworkpiece supported by the work spindle, the tool spindle is adapted toreceive either a rotary cutting tool or a stationary single-point toolfrom an adjacently positioned tool storage magazine. To accomplish this,the tool spindle is adapted to releasably receive and fixedly retaineither a nonrotatable tool, such as a lathe tool, or a rotatable toolsuch as a milling cutter or drill.

The tool storage magazine is adapted to receive a plurality of metalcutting tools including nonrotatable tools and tools adapted to beselectively rotated for performing metal cutting operations. A tooltransfer or interchange member is mounted for selective power drivenmovement to effect an interchange of tools between the tool spindle andthe tool storage magazine. Either single-point tools or rotatable toolscan be selectively interchanged between the tool storage magazine andthe tool spindle which is adapted to receive and operate either anonrotatable tool or a rotatable tool.

A principal object of the invention is to provide an improved velocitycontrol for an interchange mechanism of a machine tool.

Another object of the invention is to provide an improved automaticlatching mechanism operative to releasably clamp a member to betransferred to a selectively movable machine tool transfer arm.

Another object is to provide a power operated tool transfer arm havingan improved velocity control in combination with improved latching meansadapted to releasably clamp a member to the arm during transfer movementthereof.

Another object is to provide a simplified velocity control for a poweroperable transfer arm that automatically accelerates the rate ofmovement at the start of a transfer cycle and automatically deceleratesthe rate of movement toward the completion of the same transfer cycle.

Another object is to provide an improved interchange mechanism for amachine tool having improved means for automatically clamping a memberinto the interchange mechanism in combination with a cooperatingvelocity control for increasing the speed of transfer movement during aninterchange cycle.

Another object is to provide an improved velocity control for greatlyaccelerating operation of an interchange transfer mechanism.

Another object is to provide an improved interchange mechanism foraccelerating transfer movement of extremely heavy workpieces.

BRIEF DESCRIPTION OF THE DRAWINGS

The obvious features and advantages of the present invention will becomemore apparent from the following detailed description of preferredembodiment shown in the accompanying drawings, in which:

FIG. 1 is a view in side elevation of a machining center incorporatingthe present invention and having a tool changer disposed to operate incoordinated relationship with a work changer;

FIG. 2 is a view partly in vertical section and partly in elevation ofthe machine shown in FIG. 1, as viewed from the rightward end;

FIG. 3 is an enlarged, detailed view in vertical section through thework change arm and drive therefor;

FIG. 4 is an enlarged view of the work change arm for effecting aninterchange of workpieces between the storage position and the operatingposition;

FIG. 4A is a fragmentary view showing the pivot link engaged andactuating the linkage mechanism 123;

FIG. 4B is an enlarged fragmentary view showing the chuck 186disengaged;

FIGS. 4C to 4F inclusive are enlarged fragmentary views of a modifiedform of tool change arm 112X;

FIG. 4G is a chart showing the velocity control of workpiece armrotation;

FIGS. 5A to 5F inclusive illustrate the general sequence of movements ofthe work change arm during a cycle of movements in effecting aninterchange of workpieces between the storage position and the operatingposition;

FIGS. 6A to 6H inclusive illustrate the angular position of the velocitycontrol cam in coordinated relationship with effecting positioning ofthe valve aperture for controlling the velocity of workpieces during anautomatic interchange between operating and stored positions;

FIG. 7 is a schematic, diagrammatic block diagram of the hydraulic drivecircuit for actuating the velocity control cam to effect a selectiveinterchange of workpieces;

FIG. 8 is a view in transverse vertical section through a velocitycontrol valve having one portion responsive to the control cam andanother portion coordinately responsive to the hydraulic controlcircuit;

FIG. 8A is a top plan view of the valve shown in FIG. 8;

FIG. 8B is a view in transverse section through the valve shown in FIG.8 and shown along the plane A--A therein;

FIG. 8C is an enlarged, fragmentary view of the velocity control valvespool in FIG. 8;

FIG. 9 is a simplified form of rate control for controlling aninterchange cycle;

FIG. 9A illustrates the angular displacement of the velocity control camof the simplified rate control in degrees; and,

FIG. 9B illustrates the velocity control of the work of the simplifiedcontrol during the 90° approach, the 180° work change cycle, and the 90°return movement to parked position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and specifically to FIGS. 1 and 2 thereof,a machining center incorporating the features of the present inventionis there shown in side elevation. As illustrated in FIG. 1, the machinecomprises generally an elongated supporting bed 30 which slidablysupports a work spindle headstock 31 at one end in operative relation toa relatively movable tool supporting cross slide 35 at the other endthereof. To this end, the top surface of the bed 30 is provided withhorizontal ways 32 which are engaged by complementary ways 33 formed onthe underside of the headstock 31.

Movement of the work spindle headstock 31 in either direction iseffected by rotating a screw 34 which is in threaded engagement with arecirculating ball bearing nut 36 that is fixed to the under surface ofthe headstock 31. The screw 34 is rotatably supported in suitablebearing structures (not shown) provided in the bed 30. A motor 37carried within the interior of the hollow bed 30 is connected to rotatethe screw 34 in either direction for selectively actuating the headstock31 in its path of travel by power.

Positioning control for effecting the desired positioning movement ofthe headstock 31 to present a workpiece carried thereby at a selecteddesired position relative to a cutting tool is accomplished by operationof a cooperating scale 38 and sensing head 39. The exemplary embodimentshown in FIG. 1 comprises essentially the linear scale 38 which ismounted on the side of the headstock 31 for movement therewith andrelative to the cooperating sensing head 39 which is fixedly secured tothe side face of the bed 30. Cooperative coaction between the sensinghead 39 and scale 38 provides an accurate feedback signal to indicatethe position of the headstock 31 along the bed 30, and both the scaleand sensing head are well-known commercially available units.

The headstock 31 rotatably supports a horizontally disposed workpiecespindle 41 constituting the machine work station that is adapted toreceive a workpiece W for rotation therewith. The spindle 41 isrotatably driven at a selected one of a plurality of speeds obtainedfrom a selectively shiftable transmission 42 carried within theheadstock and diagrammatically shown in FIG. 7. The output of thetransmission 42 is transmitted to the spindle via a gear cluster 43which is selectively shiftable into meshing engagement with one oranother pair of spindle drive gears 44 and 46 that are secured directlyto the spindle 41. As diagrammatically illustrated in FIG. 7, power todrive the transmission 42 is obtained from an electric motor 47, and itis also supported within the headstock 31. Power from the motor 47 istransmitted to the transmission 42 and thence through a directionaldrive clutch mechanism (not shown) that is contained therein. It will beapparent that the motor 47 is energizeable to drive the transmission ata selected speed for, in turn, driving the workpiece spindle 41 at aselected speed in a clockwise or counterclockwise direction of rotation.

With power drive to the headstock spindle 41 discontinued, the workpiecespindle 41 is stopped in a predetermined angular position. To achievethis result, the normal power drive to the spindle from the motor 47 isdiscontinued and the spindle driven at a creep rate until it has beenrotated into a predetermined angular position.

To accomplish this, a separate variable speed servo drive mechanism 49is connectible to rotate the tool spindle 41 independently of the powerdriven transmission 42. It will be understood that the servo drivemechanism 49 is operable to rotate the workpiece spindle 41 into apredetermined angular position with respect to a tool receiving operator56. Depending upon the selected mode of operation of the workpiecespindle 41, the tool operator or spindle 56 is adapted to receive a toolindicated generally at 55 in FIG. 1 that is operative to perform theappropriately required metal cutting machining operation. In otherwords, the tool spindle headstock 35 shown in FIG. 1 is provided with atool spindle 56 that is selectively operative to releasably receive anonrotatable tool 55A which is fixedly clamped against rotation inpredetermined angular relationship to the spindle 56 for the performanceof a lathe-type operation. Upon bodily removal of the single point tool55A from the tool spindle 56, a rotatable tool such as a milling cutteror drill is operatively insertable therein and the tool spindle 56 powerdriven at a selected rate of rotation by means of a variable speed powerdriven transmission (not shown).

To support a selected tool 55 for movement relative to the cooperativelydisposed workpiece spindle 41, the tool operator 35 is carried by aslide member 59 provided with inwardly extending way surfaces (notshown) that are maintained in continuous sliding engagement with spacedapart ways 60 presented by a selectively movable hollow guide structure61. In a similar manner, the underside of the guide structure 61 isprovided with laterally spaced apart guidways (not shown) which aremaintained in slideable engagement with laterally spaced aparthorizontal ways presented by the upper portions of the stationary bed30. Only one of the longitudinally extending, horizontal ways 63presented by the bed 30 is illustrated in FIG. 1. It will be readilyapparent that the longitudinal way 63 cooperates with a similarcorresponding rearwardly spaced apart way (not shown) presented by thebed 30 in a manner to support the guiding structure 61 for horizontal,longitudinal movement along a Z axis relative to a workpiece W carriedby the work spindle 41. Separate and independent power drive means (notshown) are respectively connected to effect selective, reversiblemovement of the guiding structure 61 along the Z axis, as well as toeffect movement of the slide member 59 along the angular ways 60presented by the guide structure 61, and along the C axis parallel tothose ways. It will be readily apparent that any cutting tool 55 carriedby the tool operator 35 is thereby selectively movable along either theC axis or along the Z axis, depending upon the mode of operation of thecooperatively disposed work spindle 41.

For storing a plurality of metal cutting tools to be selectively used inthe tool spindle 56, a tool storage magazine 66 is rotatably journalledfor selective indexable rotation about a horizontal axis against therearward face of a vertically outstanding support frame 67 carried bythe bed 30. Upon selective indexable movement of the tool storagemagazine 66, a next required tool carried thereby is indexably advancedinto a forwardly extending tool change position substantially parallelto the axis of a tool, such as the tool 55A, illustrated as then beingcarried by the tool spindle 56. Upon arrival of the required tool inforwardly extending position and in the tool change station spacedrearwardly from the spindle 56, a tool change arm 71 is selectivelymovable through a tool change cycle in a manner to effect an interchangeof tools between the tool spindle 56 and a tool indexing socketpresented by the tool storage magazine 66. The arrangement for effectingsuch a tool interchange between a tool storage magazine and tool spindleis illustrated and fully described in the prior filed U.S. Pat.application entitled, "Machine Tool" with the Ser. No. 641,435. Inparticular, attention is directed to the fact that the prior filed U.S.application includes a complete description of an indexable tool storagemagazine operatively disposed to indexably position a tool into aforwardly extending tool change station in predetermined, parallelspaced relationship to a tool carried by a tool spindle. Likewise, theprior described patent application provides a selectively movable toolchange arm 71 operative to selectively and bodily transfer tools betweenthe tool spindle 56 and the tool change station afforded by theindexable storage magazine 66. It should be noted that the priormentioned patent application describes a tool storage magazine that isindexable about a vertical axis and is provided with a plurality ofradially extending storage sockets individually indexable into anaxially parallel position relative to the tool spindle there shown.Although the tool storage magazine of the prior application wasindexable about a vertical axis, the mode of operation of that machineboth with respect to the storage magazine, the associated dual purposetool spindle, and the relatively movable tool change arm aresubstantially similar to the like identified members of the presentpatent application.

It will be apparent that the selected mode of operation of the workpiecespindle 41, FIG. 1, depends upon the required sequence of operations ofa workpiece W carried thereby. A program of operations may includeturning operations that require axial rotation of the workpiece spindle41 relative to an associated single point tool 55A fixedly carried bythe associated dual purpose tool operator 35. During such an operation,it will be apparent that the slide member 59 may be selectively movedalong the C and Z axis in selectively coordinated relationship withmovement of the work spindle 41 along an associated axis. In anyworkpiece such as W in FIG. 1, a plurality of different operations suchas turning, milling, drilling, boring and tapping may be required in anypredetermined sequence, depending upon the workpiece configuration. Forbrief illustrative purposes, assume that a milling operation is to beperformed on the vertical front face 73 of the workpiece W. To do this,the tool storage magazine 66 is indexed to position such a millingcutter at the tool change station in a rearwardly spaced positionrelative to the tool spindle 56 of the tool operator 55. In thedescribed example, subsequent operation of the tool change arm 71effects a return movement of the turning tool 55A from the spindle 56 tothe magazine 66 and a concomitant forward transfer movement of therotatable face milling cutter to the spindle 56. With a face millingcutter then operatively carried by the tool spindle 56, the latter isrotatable under power as well as being rectilinearly movable by anassociated power translator, to perform a face milling operation on thefront vertical face 73 of the workpiece W.

During such an operation, and depending upon the requirements of theexact configuration of the workpiece faces 73, the work spindle 41 isselectively movable along a plurality of associated paths. Afterutilizing the tool spindle 56 to perform a preselected plurality ofdifferent machining operations on a selected workpiece, such as theworkpiece W in FIG. 7, an interchange of workpieces is effected betweenthe operating work spindle 41 and the work receiving storage station 51,as shown in FIG. 7. As there shown, the axis of the work receivingstorage station 51 is disposed in horizontal parallelism to the axis ofthe workpiece holding or headstock spindle 41. As also shown in FIG. 7,the tubular support frame 75 is provided with an axial bored opening 76within which is carried a quill 78. A workpiece storage spindle 80journalled within the quill 78 is normally constrained therein againstrotation, and in predetermined angular relationship to a correspondingpredetermined angular position of the operating workpiece spindle 41within the spindle headstock 31.

Toward its inner or lower end as viewed in FIGS. 1 and 2, the pivotalworkpiece storage frame 75 is provided with a pair of transverse boredopenings 88 that engage the opposite ends of a shaft fixedly secured toand extending through the upper end of a bracket secured at its lowerend to the bed 30 to the workpiece spindle 41. Only one of the boredbearing openings 88 in the pivotal frame 75 together with the stationarysupport shaft 89 are shown in FIG. 1.

For moving the frame 75 pivotally relative to the support shaft 89, apair of piston rod support brackets are pivotally secured in axialalignment to the opposite side faces of the frame 75; this arrangementis illustrated in FIG. 1 in which the bracket 92 is journalled to a stubshaft 93 affixed at its inner end to the side face of the frame 75. Thebracket 92 is secured to the upper end of a piston rod 94 that extendsdownwardly within a yoke 95 and attached tubular piston 96 adapted totelescopingly receive the inner end of the piston rod 94. The inner faceof the yoke 95 is pivotally secured to the vertical side face of abracket 90 affixed to the frame along an axis aligned with 97 asindicated in FIG. 1. The upper end of the piston 96 is fixedly securedto the underside of the yoke 95 and cooperates therewith in tubularfashion to receive the piston 94 as hereinbefore explained.

As shown in FIG. 2, a yoke 95A is pivotally secured to the opposite sideface of the bracket 90 and is likewise integrally secured to the upperend of a downwardly depending tubular piston 96A. The piston 96A and theyoke 95A also cooperate in tubular fashion to receive the downwardlydepending portion of a piston rod (not shown) that is pivotally securedat its upper end to the inner vertical face of the frame 75. The dottedline 98 in FIG. 2 indicates the position of a horizontal shaft thatextends transversely through the vertically upstanding bracket 90. Therespective outer ends of such a shaft, positioned along the dotted line98 as described, pivotally support the axially spaced apart yokes 95 and95A together with the downwardly depending tubular pistons respectivelysecured thereto. Actuation of the respective, spaced apart fluidactuators 96 and 96A, FIGS. 1 and 2, moves the frame 75 from thevertical manual work loading position there shown into horizontalparallel alignment with the tool spindle 41 in FIG. 7; in other words,the frame 75 and workpiece carried thereby are moved into the workreceiving storage station identified at 51. Subsequent to pivoting theframe 75 about the transverse shaft 89, a workpiece WM carried therebyis in horizontally parallel alignment with the workpiece W in thespindle 41. In further preparation for a workpiece interchange, thetranslating screw 34 shown in FIG. 1 is selectively actuated to effectthe necessary axial alignment of the workpiece W with the workpiece WMwhich is then in the workpiece storage station 51 in FIG. 7.

The workpieces W and WM are respectively secured to uniformly shapedcircular fixture rings 102 and 103 by means of radially movable clamps104 and 105 respectively mounted in annularly spaced relationship on thefixture rings. Each of the fixture rings 102 and 103 comprises auniformly shaped base section particularly adapted to be retained inreleasable clamping engagement with the respective work spindles 41 and80 as shown in FIG. 7. Each fixture ring 102 and 103 is provided withreleasable chuck mechanisms 108 and 109 on which the clamps 104 and 105are movably mounted for selective radial movement into clampingengagement with the workpieces W and WM.

It will be apparent that this arrangement renders the fixture rings 102and 103 selectively operable to releasably clamp selected ones of a widerange of different sizes and shapes of workpieces for selective andreleasable transfer movement to the operating workpiece spindle 41 shownin FIGS. 1, 2 and 7. It will be further apparent that this arrangementpermits unloading a completely machined workpiece from one fixture ring,after it is returned from the workpiece spindle 41 to the work receivingstorage station 51 and thence pivoted to the vertical unloading stationshown in FIG. 1. As this occurs, a different workpiece previouslytransferred to the workpiece spindle 41 is being machined. Likewise, anext workpiece to be machined is manually loaded into the verticallypositioned spindle support 75 in FIG. 1. It will be understood that anext workpiece is actually secured within the radially movable chuckjaws of the chuck mechanism 108 secured to the fixture ring 103. Withthe latter releasably clamped to the spindle support, the spindlesupport 75 is again pivoted 90° in a forward direction as previouslyexplained and into the work receiving station 51 illustrated in FIG. 7.

As shown in FIGS. 1, 2 and 3, a workpiece change arm 112 is in avertical parked position between the horizontal workpiece spindle 41 andthe vertically positioned spindle support 75. The change arm 112 isjournalled to rotate on an upstanding portion of the main support frame30A; it is selectively operative to effect a bodily interchange ofworkpieces between the workpiece spindle 41 and the workpiece storagespindle 80 whenever the latter is moved into the horizontal workreceiving storage station 51 shown in FIG. 7.

To effect such an interchange, the arm 112 is provided with upper andlower semicircular openings 114 and 115 extending in opposite directionsand respectively provided with associated grips operative to releasablyengage a pair of workpieces. The upper semicircular opening isadditionally referred to as grip 114 and comprises an annularly spacedpair of hardened actuating buttons 116 and a cooperatively disposedpivot clamp or link 128 pivotally carried by a pin 129 extending fromthe arm 112. The buttons 116A and 116B are mounted on one side of thework change arm 112, and the buttons 116C and 116D are mounted in likerelationship on the opposite side of the arm. During a workpieceinterchange, the two pairs of buttons 116A, B, and 116C, D engage spacedapart portions of the circular base portion of the fixture ring groove120 in cooperation with the opposite outer faces of the buttons engagingthe opposite edges of the same groove. During a workpiece interchange,likewise, a pair of annularly spaced apart angular faces 127A and 127Bpresented by the pivot clamp 128 are maintained in clamping engagementwith other peripherally spaced apart portions of the groove 120.

As indicated in FIG. 4, the first angular flat portion 127A of the pivotclamp 128 initially and resiliently engages a circular portion of thefixture ring groove 120, in advance of the angular portion 127B and thefixed clamp buttons 116. The spaced apart flat portion 127B issimultaneously maintained in cooperating clamped engagement with a flat,angular portion 126 presented by the groove 120. Due to velocity controlcam 198 through approximately the next 20° the continued forward pivotalmovement of change arm 112 is gradually slowed to zero velocity duringwhich time the other cooperating flat portion 127B is brought intoabutting engagement with the flat surface 126 presented by the groove120. During this 20° approach interval, a torsion spring 148continuously maintains face 127A abutting the periphery of groove 120.Upon continued pivotal movement of the workpiece change arm 112 into itsinitial 90° clamped and engaged position, the rate of forward movementslows from maximum velocity at 45° to zero velocity at the 90° position.From approximately 20°, the portion 127A moves into abutting engagementwith the circular portion of the groove 120.

During a bodily interchange, a rearwardly positioned latch plate 138affixed to the pivot clamp 128 is engaged by outward clamping engagementwith the cooperatively disposed angular portion of a wedge member 142,shown in FIGS. 3, 4 and 7. The wedge member 142 is mounted for movementin a guideway 144 formed in the change arm 112, for outward extensiblemovement along a path parallel to the axially movable actuating rod 153,and into wedging engagement with the rearward face of the latch plate138. As indicated by the phantom line position of the pivot clamp 128,angular faces 127A, B are resiliently urged into rightward engagementwith one spaced apart peripheral portion of groove 120 as the two pairsof actuating buttons 116A, B and 116C, D are moved into cooperativelyspaced apart peripheral portions of the circular groove 120. It isemphasized that this condition does not occur until arrival of the clamparm 112 in its initial 90° position, and in operative clampingengagement with the workpieces. Thereupon, a solenoid 156 is deenergizedto deenergize a clamp actuator 130, FIG. 7 and permit retractingmovement of rod 153. With the rod 153 likewise released, resilientlyactuated extensible movement of the wedge actuating members 142 and 143is effected by axially expansible springs 158 and 159 in the arm 112. Tomaintain the actuating wedges 142 and 143 in retracted inward position,as illustrated in FIG. 4, it is necessary to energize the solenoid 156of a valve 157 thereby urging a valve spool 154 outwardly to pressureactuated position in opposition to the biasing spring 155. With thiscondition existing, pressure fluid is transmitted from a low pressuresupply line 162 via a line 163 in the outwardly moved valve spool, andthence via a line 164 to urge a piston 165 of the fluid actuator 130outwardly.

Outward movement of the actuator piston 165, in turn, effects axialoutward movement of the rod 153 together with the outer flanged member166 that engages the inner ends of pivotal toggle arms 167 and 168. Itwill be apparent that whenever the flanged member 166 is moved axiallyoutward in response to energization of solenoid 156, as described, theopposite inner ends of the toggle arms 167, 168 are both pivotedinwardly to retract both wedges 142, 143 axially inward. Thus, bothwedges 142 and 143 are then fully retracted to fully compress therespective actuating springs 158 and 159, whenever the solenoid 156 isenergized to effect outward movement of the fluid actuator 130 and theassociated actuating rod 153.

Conversely, as previously explained, the solenoid 156 is deenergizedafter both angular faces 133A, B are moved into full engagement with thebase 121 of the groove 121 to effect resiliently biased latching of thewedges 142 and 143 by the respective actuating springs 158 and 159.

In brief summary, the timing sequence to effect a workpiece interchangebetween the work spindle 41 and the storage spindle 80 in the storagestation 51 is as follows. Initially, the change arm 112 is rotated 90°in a clockwise direction to simultaneously engage both workpieces WM andW as described. After the workpieces are both in angularly clampedpositions within tool grips 114 and 115 of the arm in 90° position,unclamp solenoids 172 and 173 are both energized to move therespectively associated valve spools 174 and 175 to forward pressureactuated positions. Next, actuating rod 178 and 179 which are normallyurged forward by springs 182 and 183 are both retracted axially inresponse to energization of the unclamp solenoids 172 and 173. Axialretraction of the rods 178 and 179, in turn, is disposed to effectpivotal retraction of the chuck jaws associated with the respectivepower actuated chuck mechanisms 186 and 187.

After this takes place, a next solenoid 189 is energized to effectmovement of an associated valve spool 190 to its upper position as shownin FIG. 7. Pressure fluid is then transmitted via pressure lines 192 and193 to release the clamping pressure applied to pressure actuators 194and 195. Inasmuch as the power actuated chucks 186 and 187 are thenfully released, the described activation of both power actuators 194 and195 effects bodily axial retraction of both spindles 41 and 80 fromengagement with the fixture rings 103 and 102. Prior to this, both thefixture rings 103 and 102 together with the associated workpieces WM andW are then releasably clamped to the workpiece change arm 112 positionedin its initial 90° position.

As shown in somewhat greater detail in FIGS. 4B and 7, each of the poweractuated chucks comprise a plurality of pivotal jaws pivotally securedto the outer ends of the respective work spindles 51 and 41. As shown inFIG. 4B, for example, jaws 184 and 184A are pivoted angularly outwardrelative to the storage spindle 51. The respective clamp jaws 184 and184A are pivotally secured within radial slots formed in a mountingcollar 181 fixedly secured directly to the outer end of the storagespindle 51. An annular locking plate 185 is resiliently secured to theouter end of the actuating rod 178 by a spring 185A maintained inposition by a cap screw 185B engaging the outer end of the actuating rod178.

As will hereinafter be more fully described, a velocity control cam 198effects directionally controlled operation of a power drive 199 torotate a tubular drive shaft 201 to continue rotation of the change arm112 an additional 180° in a clockwise direction. After the change armhas rotated 180° further in a clockwise direction, the respectiveworkpiece grips 114 and 115 are now in pivotally interchanged positionwith the retracted spindles 41 and 80 respectively. In other words, theworkpiece WM carried within the grip 114 is now axially aligned with thework spindle 41 and the workpiece W carried within the grip 115 is nowaligned with the storage spindle 80. After the initial interchangedalignment has been achieved, as described, the solenoid 189 isdeenergized and the associated valve spool resiliently biased to itsopposite or return position. With the valve spool 190 urged to itsopposite position by the spring 204, pressure fluid is transmitted via adrilled line 205 therein to a transmission line 208. With the line 192connected to exhaust and the line 208 connected to again actuate thefluid actuators 194 and 195 in a forward direction, the fluid actuatorsare again operated to effect axial forward movement of the spindles 80and 41. The spindles 41 and 80 are moved forward into the nowinterchanged fixture rings 103 and 102 together with the associatedworkpieces WM and W carried thereby.

Completion of the described workpiece interchange is effected upondeenergization of the clamp solenoids 172 and 173, as soon as poweractuators 194 and 195 effect axial relative return between the spindlesand the now interchanged fixture rings. Deenergization of solenoid 172effects resilient return of the valve spool 174 by the spring 210. Uponresilient return of the valve spool 174 to the position shown in FIG. 7,a fluid pressure line 211 is connected via a line 212 in the upwardlymoved valve spool to a supply line 213 connected to effect axial forwardmovement of the actuating rod 178 by actuating spring 182. At the sametime, deenergization of solenoid 173 permits resilient return of thevalve spool 175 by the spring 215 to the position illustrated in FIG. 7.During this condition, solenoid 176 is retained in energized conditionto retain the valve spool 177 positioned to transmit fluid pressure tothe branch supply lines 180 and 380. With this condition existing,deenergization of the solenoid 173 permits the spring 215 to effectupward movement of the valve spool 175 and connection of the pressureline 180 via the transverse valve spool line 216 to the output line 217.

It is reiterated that engagement of the respective semicircular openings114 and 115 formed in the arm 112 does not actually occur until the armhas rotated 90° in a clockwise direction from its vertical parkedposition. As such a 90° rotation of the arm 112 occurs, the linkagemechanism 123 functions to resiliently bias the links 128 and 134 aboutthe respective pivot pins 129 and 135 which are carried for bodilymovement by the arm 112. As shown in FIG. 4, the respective pivot links128 and 134 are operatively interconnected to a central actuating link145 that is pivotally secured to a rotatably journalled pin 146. Asshown in FIG. 3, an inner or rearward portion of the centrallyjournalled actuating link 145 is interconnected by means of a torsionspring 148 to the inner face of the tool change arm 112. Referring againto FIG. 4, it will be noted that an actuating rod 150 is pivotallyinterconnected between one end of the centrally disposed actuating link145 and the upper end of the pivotal latching link 128. In like manner,another actuating rod 151 is pivotally interconnected at its oppositeends to one end of the central actuating link 145 and the lower pivotallink 134. The arrangement is such that power driven clockwise movementof the workpiece change arm 112 effects 90° movement of the respectiveopenings 114 and 115 into engagement with the grooves 120 and 121presented by the fixture rings 103 and 102, thereby moving the buttons116 and 117 into engagement with the grooves.

As the arm 112 rotates into such engagement, the angular faces 127A oflink 128 and angular face 133B of link 134 resiliently engage therespective fixture ring grooves 120 and 121 first. The torsion spring148 resiliently urges the linkage mechanism 123 to rotate in a clockwisedirection until the links 128 and 129 fully engage the respectivegrooves 120 and 123 in opposition to the sets of buttons 116 and 117engaging spaced apart portions of the same grooves. As soon as this 90°position is achieved, the angular flats 127B and 133B presented by thelinks 128 and 134 are respectfully biased into engagement with the flatsurface 126 and 132 formed on the associated grooves 103 and 102.

By means of this arrangement, the individual workpieces and theirrespectively associated fixture support rings 102 and 103 are alwaysretained in predetermined positions in the machine. This applies both tothe axial and angular position of the workpiece in the storage spindle80 and the relative corresponding positions of the workpiece in theworkpiece spindle 41. Prior to effecting an interchange of workpieces,therefore, the workpiece spindle 41 is moved into a predetermined axialand angular position relative to the storage spindle 80. After thespindles 41 and 80 have been moved into predetermined correspondingpositions, a work change arm 112 is selectively operative to effect abodily interchange of workpieces between the respective spindles 41 and80.

In addition to effecting the interchange, the movable change arm 112 isprovided with a coordinately operative linkage mechanism adapted tocooperate with the fixture rings 102 and 103 to retain them in likerelative positions during the interchange. Furthermore, both of the workspindles 41 and 80, as well as the fixture rings 102 and 103 areequipped with cooperatively disposed annular clutch teeth that areengaged after the interchange is completed to retain the fixture ringsin the same relative angular alignment.

In FIGS. 4C to 4E inclusive, there is illustrated a workpiece change are112X of slightly modified form. Although operative to perform the samework changing function as the change arm 112 illustrated in FIG. 4, thechange arm 112X is provided with oppositely oriented semicircular toolgrip openings 114X and 115X adapted to directly engage circular timinggrooves in the tools. As shown in FIG. 4C, for example, the oppositelyoriented semicircular openings 114X and 115X are respectively presentedby the change arm 112X in positions to be moved into direct engagementwith the circular grooves 120 and 121 in the tool fixture support rings103 and 102. As the semicircular change arm openings 114X and 115X aremoved into direct controlling engagement with the circular grooves inthe support rings 103 and 102, the respective rotatable control links128 and 134 are cooperatively moved into pivotal engagement with spacedapart portions of the respective fixture rings 103 and 102. In otherwords, both of the links 128 and 134 are pivoted into full clampingengagement with the fixture rings 103 and 102 after which the links 128and 134 are releasably secured to the tool change arm 112X in pivotallyclamped positions.

The linkage mechanism 123X is provided with spaced apart actuatingsprings 252 and 253 in lieu of the single, centrally located torsionalactuating spring 148 shown and desscribed in FIG. 3. With the change arm112 in vertical retracted position, the spaced apart springs 252 and 253are adapted to resiliently maintain the pivotal links 128 and 134, aswell as the entire linkage mechanism 123X in retracted position tocooperate with the change arm 112 to facilitate a workpiece interchangebetween the spindles 41 and 80. As hereinbefore described, the workpiecechange arm 112X is in a vertically upstanding position at the start of aworkpiece interchange cycle. From the vertical position, the change arm112X is rotated in a counterclockwise direction (as viewed from thefront) in FIGS. 4C, 4D and 4E. Upon arrival of the change arm in theposition shown in FIG. 4C, the angular face 127A of the pivotal link 128moves into abutting engagement with the circular periphery of thefixture ring 103. The spring 252 is connected at one end to a fixed pin256 secured to the arm 112X and at its opposite end to a fixed pin 256secured to the face of the pivot link 128 to effect pivotal movement ofthe latter counterclockwise relative to its pivotal support pin 129.

As the change arm 112X continues to rotate in a counterclockwisedirection at a gradually reducing speed rate, the angular face 127A ofthe pivot link 128 is resiliently maintained in abutting and controlledengagement with the fixture ring 103. Due to the resiliently urgedabutting engagement between the angular face 127A and the ring 103, thepivot link 128 is urged to rotate in a counterclockwise direction aboutthe pivot pin 129 as the change arm 112X continues to be rotated in acounterclockwise direction. Upon further counterclockwise rotation ofthe pivot link 128 the opposite angular face 127B thereof is graduallyrotated into abutting engagement with the angular positioning face 126presented by the fixture ring 103, as shown in FIGS. 4D and 4E. Afterthis occurs, the groove of the fixture ring 103 is maintained in fullyclamped engagement between the semicircular tool grip opening 114X andthe actuated clamp jaws 127B. Once the clamp is fully closed, as shownin FIG. 4E, the angular face 127B is maintained in clamping engagementwith the angular face 126 of the fixture ring 103 to prevent rotation ofthe fixture ring during rotational movement of the work change arm 112to effect a workpiece interchange.

Simultaneously with movement of the grip 114X into the describedposition in FIG. 4E, the opposite grip 115X and pivot link 134 are movedinto coordinate positioning engagement with the fixture ring 102. Next,as hereinbefore explained, both of the extensible wedges 142 and 143 aremoved axially outward into latching engagement with the respective latchplates 138 and 139 secured to the rearward faces of the pivotal links128 and 134. This arrangement has been described in connection with FIG.7 in which the springs 158 and 159 are illustrated as positioned to urgethe wedges 142 and 143 into latched positions.

Likewise, as shown in enlarged fragmentary form in FIG. 4F, theextensible wedges 142 and 143 are shown in laterally displaced offsetpositions relative to the central actuating rod 153. For retracting thetapered wedges, a vertically upward force is applied to the lower end ofthe rod 153 to pivot the outer ends of toggle arms 167 and 168 downwardto retract the wedges 142 and 143. Conversely, after the change arm 112is moved to the clamped position shown in FIG. 4E, the retracting forceis removed from rod 153. After this, the springs 158 and 159 exert avertical latching force on the extensible wedges 142 and 143. Thus, thewedges 142 and 143 are continuously maintained in resiliently biasedlatching engagement with the respective latch plates 138 and 139 securedto the pivotally engaged links 128 and 134. The respective fixture rings102 and 103 are maintained in fixedly clamped engagement within thesemicircular outer ends 114X and 115X of the workpiece fixture arm 112.After being so secured, both fixture rings 103 and 102 are positivelysecured in locked positions and are likewise constrained againstrotation. Prevention from rotation is effected by the locked engagementbetween the angular pivot link faces 127B, 133B and the angular flatsurfaces 126 and 132 on the respective fixture rings. Holding the rings103 and 102 in predetermined angular positions during an interchange isnecessary for positioning a fixture ring and workpiece carried therebyin predetermined angular position in the spindle 41. To achieve desiredangularity therefore, the workpiece in the storage spindle 80 ispositioned at the desired angle and the workpiece in the spindle 41 ispositioned at the desired angle.

Angularly tapered inner faces on the latch plates 138 and 139 areengaged by complementary angularly tapered faces on the axially outwardextended wedges 142 and 143. Due to the tapered faces, the springs 158and 159 exert sufficient outward pressure to positively maintain thewedges 142 and 143 in latched engagement with the plates 138 and 139during rotational movement of the change arm 112.

The sequence of movements during an interchange are graphicallyillustrated in FIGS. 5A to 5F inclusive. As there shown in FIG. 5A, thework change arm 112 is in vertical position between the fixture rings102 and 103 respectively carried by the workpiece spindle 41 and thestorage spindle 80. From its vertical position shown in FIG. 5A, theworkpiece change arm is rotated in a clockwise direction to the positionillustrated in FIG. 5B to position the semicircular grips 114 and 115into engagement with fixture ring grooves 102 and 103. During the first90° of movement, the power drive for the change arm 112 increases fromzero velocity to maximum speed at approximately the 45° position;velocity then again decreases with zero speed being reached at the 90°position.

After the fixture rings 102 and 103 are securely clamped in the toolgrips by resilient closure of the wedges 142 and 143 with the plates,both spindles are unclamped. As shown in FIG. 5C, both spindles 41 and80 are moved to axially retracted position thereby disengaging them fromdriving positions. Both the storage spindle 80 and the workpiece drivespindle 41 are provided with forward driving ends comprising annularteeth 224 and 225 respectively. Prior to retraction, the forward drivingends 224 and 225 of the spindles 80 and 41 are maintained inintermeshing driving engagement with driven portions of the respectiveworkpiece fixture rings 103 and 102 and comprising intermeshing annulargear teeth. This relationship is more clearly indicated in FIG. 7 inwhich the annular driving teeth 225 of the workpiece spindle 41 areseated in driving engagement with complementary annular driven teeth 227on the fixture ring 102. In a similar manner, as shown in FIG. 7, theannular teeth 224 on the forward end of the storage spindle 80 areseated in driving engagement with complementary annular teeth 226 on thefixture ring 103.

After the spindles 80 and 41 have been retracted to the positions shownin FIG. 5C, the workpiece change arm 112 is rotated an additional 180° Cin a clockwise direction to the position shown in FIG. 5D. During this180° rotation, the power drive for the arm 112 increases speed from zeroto maximum in the first 45°; sustains the maximum speed during the next90°; and, again gradually reduces speed from maximum to zero during thelast 45°. Throughout this 180° interchange, the fixture rings 102 and103 are fixedly clamped in the opposite ends of the change arm 112 asdescribed. Upon arrival in the 180° interchanged position in FIG. 5D,the annular driven teeth (not shown) of the fixture rings 103 and 102are angularly positioned to engage the complementary angular spindleteeth 225 and 224. Because of this, angular alignment of the cooperatingteeth merely actuate the power drives for effecting axial forwardmovement of the workpiece spindles 41 and 80 into driving engagementwith the respectively interchanged fixture rings 103 and 102.

After the spindles 41 and 80 have been reengaged with the nowinterchanged fixture rings 103 and 102, as shown in FIG. 5E, the spindlechucks 186 and 187 are both reengaged. The central actuating rod 153 isthen operated to effect power operated retraction of the wedges 142 and143 within the workpiece change arm 112. Power actuated retraction ofthe wedges 142 and 143 from engagement with the latch plates 138 and 139releases the pivotal links 128 and 134 for subsequent resilient returnto home position. The sequence of operations has now proceeded to apoint at which the properly angularly oriented interchanged fixturerings 103 and 102 are respectively and positively clamped to theworkpiece spindles 41 and 80. Further, with the pivotal links 128 and134 released, the power drive pivotally rotates the workpiece change arm90° in a counterclockwise direction to vertical parked position asviewed in FIG. 5F. As explained with reference to FIG. 3, the torsionspring 148 operates to return both pivotal links 128 and 134 to homeposition as the latter are moved out of engagement with theinterchangeed fixture rings 103 and 102. Both links 134 and 128 are inthe resiliently returned starting position as the workpiece change arm112 is power driven 90° in a counterclockwise direction to the verticalparked position shown in FIG. 5F. Likewise at the completion of aworkpiece interchange, the tubular support frame 75 is power driven toits vertical position as shown in FIG. 5F for facilitating a manualchange of workpieces.

After one workpiece interchange has been effected as described in FIGS.5A to 5F inclusive, the workpiece change arm 112 has advanced a total of180° from the first to the last view in this series. The next cycle ofmovements for a second workpiece interchange is performed in like mannerwith movement of the work change arm 112 starting from the verticalposition shown in FIG. 5F. The cam 198 for controlling movement andvelocity of the change arm 112 functions in a manner identical to thathereinbefore described for FIGS. 5A to 5F inclusive.

As mentioned in connection with FIG. 7, each workpiece interchange cyclecomprises three distinct individual segments of rotational movement ofthe workpiece change arm 112. These include a 90° clockwise segment intoworkpiece engagement, a 180° clockwise segment for interchangingworkpiece position between the spindles, and a 90° counterclockwisesegment to return parked position. Each segment of movement comprises anaccelerating portion during which speed is increased from zero to apredetermined maximum velocity at approximately 45° of movement; and adecelerating portion during the last 45° of each segment of movement inwhich speed is decreased from the predetermined maximum to zerovelocity. During the second or interchange segment of movement, velocityremains at the maximum for 90°, or from 135° to 225° with thedecelerating portion of this cycle extending from 225° to 270°. Thethree segments of rotational movement of the work change arm 112 areselectively interspersed in predetermined sequence between otherrequired movements of the workpiece spindles 80, 40 and the power drivestherefore that are necessary to effect an interchange of workpieces.

These rotational velocity relationships of the workpiece change arm 112are clearly and graphically illustrated in FIG. 4G in which the initialor starting 90° clockwise approach segment of movement comprises the 45°accelerating portion 230 and the 45° decelerating portion 231. Next, theworkpiece interchange is effected in the next 180° of movementcomprising a 45° accelerating clockwise segment of movement 233; maximumvelocity being maintained for 90° during continued clockwise movement asindicated at 234; and with a decelerating clockwise portion of movementoccuring during the last 45° as indicated at the solid line portion 235.After the interchange is completed, as indicated at the 270° position in4G, the workpiece change arm 112 is returned to a vertical parkedposition in a counterclockwise direction. The last portion of movementcomprises a 45° counterclockwise accelerating segment indicated at thedotted line portion 238 and a 45° decelerating portion indicated at thedotted line portion 239 in FIG. 4G. Movement is stopped in the 180°vertical parked position corresponding to the completed sample cycleillustrated in FIG. 5F.

At the completion of the first interchange of workpieces between thestorage spindle 80 and the workpiece spindle 41, as described, it willbe apparent that the velocity control cam 198 is actually displacedangularly 180° from its starting position. Inasmuch as the velocity cam198 is symmetrical in configuration, this has no effect on the nextinterchange of workpieces between the storage spindle 80 and 41, androtational velocity is again controlled as indicated in FIG. 4G.

In order to control the accelerating and decelerating velocity portionof each segment of movement, the control cam 198 is rotatably driven bythe tubular change arm drive shaft 201 that is connected to be driven bythe reversibly and rate controlled power drive 199 for effectingrotatable movement of the workpiece change arm 112. The power drive 199comprises a reversible fluid drive motor 260 and geared transmission 261operatively interconnected to rotatably drive the tubular shaft 201which, in turn, is connected to rotate the workpiece change arm 112 andvelocity control cam 198. The drive transmission 261 includes an outputshaft 262 driven directly by the motor 260 and gear 263. The latter isinterconnected to drive a gear 264, shaft 265, and gear 266 connected torotate gear 267. The latter gear is likewise connected to drive a shaftthat rotates a gear 268 intermeshing with a gear 270 secured directly tothe tubular drive shaft 201 for rotating the workpiece change arm 112.During rotation, the control cam 198 is operable to radially actuate acam roller 238 schematically illustrated in FIG. 7 as actuating acontrol arm 239 connected to selectively adjust a fluid control valve241. Biasing means (not shown) are connected in well-known manner tocontinuously urge the arm 239 and roller 238 carried thereby intooperative engagement with the periphery of the rotatable velocitycontrol cam 198. Actually, the control valve 241 comprises two separatevalves 243 and 244, the positions of both of which are connected to beadjusted by the single control arm 239 that is connected to be movedaxially upon rotational movement of the cam 198 as schematically shownin FIG. 7.

Because of the rate and motion control effected by the entire workpieceinterchange system, the sequence of movements is briefly repeated inconnection with FIGS. 5A to 5F inclusive. Initially, the workpieceinterchange arm 112 is in vertical parked position as shown in FIG. 5Arelative to the axially aligned storage spindle 80 and operatingworkpiece spindle 41. To greatly accelerate the speed of an interchangeof workpieces between the storage spindle 80 and the operating spindle41, a velocity control is operatively interconnected in the transfercontrol system as will be more fully explained. The velocity controlautomatically controls the acceleration and deceleration of movement ofthe transfer arm according to a predetermined cyclical pattern to bothaccelerate transfer movement and permit transfer of much heavierworkpieces. To further facilitate transfer movement, the automaticclamping mechanism 123 is coordinately operative to releasably controlclamping of the workpieces to the transfer arm 112 during transfermovement.

In addition to effecting movement of the spindles 80 and 41 intopredetermined axial alignment, the control system is operative to effectmovement of the workpiece spindle 41 into a predetermined angularposition relative to the storage spindle 80. Angular positioning of theworkpiece spindle 41 is required to effect predetermined angularalignment of the annular driving teeth 225 presented by the spindle 41into predetermined angular alignment with the annular drive teeth 224presented by the storage spindle 80. With the annular workpiece spindleteeth 225 in predetermined angular position relative to the storagespindle teeth 224, as viewed in FIGS. 5C and 5B, it will be apparentthat the annular teeth 227 and 226 respectively presented by the fixturerings 102 and 103 are moved into corresponding angular positions.Furthermore, the linkage mechanism 123 is disposed to cooperate with theworkpiece change arm 112 in a manner to clamp the fixture rings 103 and102 in predetermined angular alignment with the semicircular tool gripopenings 114 and 115 as hereinbefore described with reference to FIG. 4.

With the spindles 41 and 80 being moved into predetermined axial andangular positions relative to one another as shown in FIG. 5A, it isreiterated that the work change arm 112 is then moved 90° from itsvertical position in a clockwise direction as viewed from the front intofixed clamping engagement with the fixture rings 103 and 102. With thefixture rings 102 and 103 now clamped in like angular positions in thework change arm 112 as viewed in FIG. 5B, both spindles 41 and 80 areaxially retracted to the positions illustrated in FIG. 5C. With thiscondition established, i.e. the fixture rings completely disengaged fromthe spindles, the work change arm 112 is then rotated 180° in aclockwise direction as viewed from the front (counterclockwise directionas viewed from rear) to the position illustrated in FIG. 5D. Uponarrival in this position, the annular teeth 227 and 226 respectivelypresented by the interchanged fixture rings 102 and 103 are aligned forreengagement with the annular teeth 224 and 225 respectively presentedby the spindles 80 and 41. With relative axial movement again beingeffected between the spindles and the work change arm 112, the annularteeth presented by the fixture rings are moved into driving reengagementwith the annular teeth presented by the respective spindles. Thereengaged and interchanged fixture rings are then positively reclampedto the respective spindles 80 and 41 by operation of the power actuatedchucks 186 and 187. After the chucks have been reactuated to clamp theinterchanged fixture rings to the spindles, the work change arm 112 isrotated 90° in a counterclockwise direction as viewed from the front inFIG. 5F. With the workpiece interchange now completed, the work changespindle 80 is pivotally moved 90° rearwardly to the vertical parkedposition illustrated in FIG. 5F. Movement of the storage spindle tovertical position facilitates manual reloading of the storage spindlewith the next workpiece and supporting fixture ring for effecting thenext workpiece operation.

The velocity control cam 198 operates to control the rotational movementof the work change arm 112 in coordinate relationship with the othermovements necessary to effect a workpiece interchange between thestorage spindle 80 and the workpiece operating spindle 41. To simplifyan understanding of operation of the velocity control cam 198, it seemsadvantageous to describe the rate control through the initial 90°movements of the work change arm from vertical parked position toinitial engaged position; then proceed with description of the ratecontrol of the work change arm through the next 180° for actuallyinterchanging the position of the fixture rings; and finally describerate control of the work change arm through the last 90° for returningthe work change arm 112 to its vertically parked position between thetwo spindles.

As hereinbefore explained, the condition actually illustrated in FIG. 7shows the work change arm 112 after being pivotally moved 90° in aclockwise direction, as viewed from the front, into engagement with thefixture rings 103 and 102 respectively. At the start of the cycle asindicated, the fixture ring 103 is carried by the storage spindle 80 andthe fixture ring 102 is carried by the workpiece spindle 41. Foreffecting the proper directional and rate controlled movement of thechange arm motor 260, a solenoid controlled valve 282 is operative totransmit pressure fluid from a high-pressure fluid supply line 283. Thehigh-pressure control valve 282 is operated in parallel with a solenoidcontrol 286 which is connected to selectively interconnect either thevalve orifice 244 or valve orifice 243 of the rate control valve 241which is selectively controlled by the velocity control cam 198. Themotor control valve 282 is operative to transmit pressure fluid from aline 283 to effect selective directionally controlled rotation of themotor 260 and to transmit the return flow of fluid from the motor to anequalizing control valve 287. The latter valve 287 performs a continuousequalizing function on the return flow of fluid from the motor to thevalve 241 which is controlled by the velocity control cam 198. Ratecontrol of the motor 260 for controlling velocity of the arm 112 in anyof its three modes of operation, as explained in FIG. 4G, is controlledby back pressure of fluid through the valve 241 as determined by thevelocity control cam 198.

To effect the timing sequence of the rate control of the work change arm112 as schematically illustrated in FIGS. 4G and 7, there is providedthe control valve illustrated in FIGS. 8 to 8C inclusive. As shown inFIG. 8, the control valve 241 comprises a valve body 290 having a pairof horizontally disposed circular openings 291 and 292 respectively. Atubular valve sleeve 295 extends through approximately one-half theaxial length of the lower circular opening 291 and is fixedly pinnedtherein as indicated in FIG. 8. The tubular sleeve 295 contains thefluid passing rectangular orifices 247 and 248 which are selectivelyconnectable to transmit fluid from the pivotally rotatable fluid controlvalve orifices 243 and 244. To do this, the rectangular orifices 247 and248 in the sleeve 295 are in fixed, radial alignment with fluid passingorifices 297 and 298 contained in the wall between the circular openings291 and 292. The tubular valve sleeve 295 is provided with a circularopening adapted to pivotally receive the circular rate control valve241. As illustrated in FIG. 8, the tubular rate control valve 241contained a small rate control aperture or orifice 243 and a large ratecontrol orifice 244 respectively adapted to control the flow ofhydraulic fluid between a central circular valve cavity 299 within thepivotal valve 241 to one or the other of the rectangular orifices 243 or244, depending upon the axially adjusted position of the flow controlvalve 286 carried within the upper circular opening 292. For selectivelycontrolling velocity, the tubular rate control valve 241 is providedwith a rightward end 302 extending axially outward through a suitablecircular opening formed in a vertical wall member 303 fixedly secured tothe rightward end of the valve body 290 and forming a closure for therightward ends of circular openings 291 and 292. A radial arm 305secured to the rightward end 302 of the pivotal valve body 241 isengaged by the cam roller 238 which is directly engaged by the peripheryof the symmetrical velocity control cam 198, as will hereinafter beexplained in connection with FIG. 6. A torsion spring 304 engaging anon-rotatable wall member 306 engages the radial arm 305 in a manner tocontinuously urge the cam roller 238 into engagement with the velocitycontrol cam 198. Selective pivotal movement of the tubular body 241 inresponse to limited pivotal movement of the cam roller 238 as determinedby the velocity control cam 198 in turn effects selective pivotalmovement of the rate control orifice 243 and 244 to effect control ofthe fluid passing from the central circular cavity 299 within the valve241 relative to the fixed rectangular orifices 247 and 248 contained inthe tubular sleeve 295.

The axial position of the tubular control valve 286 relative to thefixed, fluid passing rectangular valves 247 and 248 depends upon whichrotational cycle is being operated. As shown in FIG. 8, a left verticalwall member 307 is fixedly secured to the leftward end of the valve body290 in a manner to operatively enclose the leftward end of the circularopenings 291 and 292 formed therein. Whenever the workpiece change arm112 is operated in either its first or third rotational cycles, a spring309 operates to bias the valve 286 rightwardly within the upper circularvalve body opening 292 to the axial position illustrated in FIG. 8. Thespring 309 is seated at its leftward end within a circular openingformed in the left end wall member 307 and extends rightwardly within ahorizontally aligned circular opening 310 formed in the axially movabletubular switch control valve 286. During the first and third rotationalcycles, therefore, the spring 309 maintains the valve 286 in its extremerightward position in a manner to align an annular valve groove 312formed therein between the fixed aperture 297 and an upper fluid line314.

During the second cycle of rotational movement, a solenoid 315 isenergized to effect downward movement of an associated valve spool,thereby transmitting hydraulic fluid from an inlet pressure line via thedownwardly urged valve spool 316 and transmit pressure fluid to an inletline 318 formed in the rightward raw member 303 of the control valve241. Pressure fluid admitted to the inlet line 318 effects leftwardmovement of the axially movable control valve 286 for reconnecting theannular valve groove 312 between the fluid passing aperture 298 and afluid line 320.

As shown and described in FIGS. 8 to 8C inclusive, there is provided abiaxial control valve having the pivotal valve spool 241 disposed in apredetermined metering relationship to the axially movable control valve286. With the valve 286 in resiliently biased rightward position asshown in FIG. 8, the valve spool 241 is selectively pivotal from anangular position in which no fluid is passed from the central valveopening 299 via the valve orifice 243 and thence through the fixedrectangular openings 247, 297 to the tubular annular groove 312. Aselectively metered flow of hydraulic fluid is then passed from theinlet cavity 299 to the annular valve groove 312 as effected bypredetermined pivotal movement of the valve spool 241 in response toengagement of the velocity control cam with the cam roller 238.

In a similar manner, energization of the solenoid 315 effects fluidactuated leftward movement of the valve 286 for aligning the annularvalve groove 312 in the leftwardly moved valve 286 between the larger,pivotal control valve orifice 244 and the interconnecting rectangularorifices to the annular valve groove.

As hereinbefore explained with reference to the velocity chart in FIG.4G, it will be readily apparent that each of the three differentrotational cycles of movement of the workpiece arm 112 comprise anaccelerating and a decelerating portion as selectively controlled by thevelocity control cam. Thus, there are in effect a total of six differentvelocity controlled segments of movement of the workpiece change arm112. In other words, two different velocity control segments of movementare provided in each of the three distinct rotational cycles of movementof the workpiece change arm 112.

In FIG. 6 there is provided a timing diagram to better illustrate thefunctional or operational relationship between the velocity control cam198, the pivotal flow control valve 241, and the axially movable orificeselection valve 286. The various interconnected parts are schematicallyillustrated in FIG. 6 to more clearly explain the mode of operation ofthe velocity control cam 198. Reading from the bottom to the top of FIG.6, there are shown eight different conditions of functional operation ofthe velocity control cam including FIGS. 6A to 6H inclusive. In eachline, the velocity control cam 198 is illustrated as engaging the camroller 238 carried by the radial arm 305 which is connected to effectselective pivotal movement of the valve spool 241. As hereinbeforeexplained with reference to FIG. 8, the pivotal movement of theresiliently biased valve spool 241 is effected by rotational movement ofthe velocity control cam 198. As shown in FIG. 6A, the cam roller isresiliently biased to extreme leftward positiion engaging a centralindented portion of the velocity control cam 198. With this conditionexisting, the small adjustable orifice 243 contained in the pivotalvalve 241 is completely disengaged from the fixed rectangular orifice247 operatively associated therewith. In other words, with the conditionillustrated in 6A, the axially movable control valve 286 is axiallybiased to its rightward position, as shown in FIG. 8, for moving thefixed rectangular orifice 247 shown therein into alignment with theorifice 243, as soon as the latter is pivoted angularly into a fluidpassing position.

As viewed in FIGS. 6A to 6H inclusive, it will be understood thevelocity control cam 198, cam follower 238, radial arm 305 and pivotalvalve spool 241 are viewed from the rear of the machine. In other words,from the cycle start position illustrated in FIG. 6A, the control cam198 is rotated in a clockwise direction to effect angular movement ofthe cam roller 238 in a counterclockwise direction to effectcounterclockwise rotation of the pivotal valve spool 241. Thereupon, thesmall valve control orifice 243 is rotated in a correspondingcounterclockwise direction to effect a gradually increasing transmissionof hydraulic fluid to the fixedly positioned rectangular orifice 247 andthe annular valve spool groove 312 positioned in the rightwardly biasedcontrol valve 286. It will be understood the gradual increase flow offluid between the smaller orifice 243 and fixed rectangular orifice 247effects a gradual increase in rate until maximum velocity is reached atthe 45° position as illustrated in FIG. 6B. To show the metering effectprovided between the adjustable orifice 243 and the fixed orifice 247,an intermediate position is illustrated in dotted form at FIG. 6AA.Continued clockwise rotation of the velocity control cam 198 effectscontinued counterclockwise pivotal movement of the cam roller 238 andvalve spool 241 to the position illustrated in FIG. 6C. During theinitial 90° approach segment of movement, it should be noted that thecontrol valve 286 is resiliently maintained in its rightward position bythe spring 309, FIG. 8, in order to maintain the axially movable tubularaxis 247 in alignment with the pivotal orifice 243 as shown in FIG. 6B.Therefore, solenoid 315 is not energized until after the pivotal controlvalve 241 has been rotated into the counterclockwise positionillustrated in FIG. 6C. In other words, the pivotally adjustable valveorifice 243 is moved completely out of engagement to the tubularlyaligned fluid passing opening 247 to effect complete deceleration of theassociated workpiece member before the rectangular aperture 247 isdisconnected and the axially spaced aperture 248 is connected to passfluid. Initially therefore the rate control condition illustrated inFIG. 6C shows the complete deceleration of the work change member as thearm is moved into engagement with the associated workpieces. Therefore,the conditions illustrated in the views 6C to 6G inclusive illustratethe operation of the velocity control cam to control the rate ofmovement of the work change arm during the 180° of workpiece armrotation to effect the actual workpiece interchange. As shown in FIG. 6,this covers rotation of the workpiece change member 198 from the 90°position to the 270° position.

As hereinbefore explained, the solenoid 315 shown in FIG. 8 is energizedto effect operation of the associated valve to transmit high pressurefluid to the line 318 thereby effecting hydraulically actuated leftwardmovement of the control valve 286. Thereupon, the annular valve groove312 is moved leftwardly to render the small aperture 243 disconnectedand the large aperture 244 of the valve 241 connected for controllingvelocity during the interchange. Either aperture 243 or 244 may beformed in the shape of a slot. As hereinbefore explained, theserelationships are accomplished by aligning the annular valve groove 312between the fixed rectangular aperture 248 and the fluid line 320. Asillustrated in FIG. 6C, the pivotal valve spool is in direct alignmentabove the rectangular aperture 248 conditioned for downward movementrelative thereto upon continued clockwise rotation of the velocitycontrol cam 198. Upon such downward pivotal movement of the valve spool241 in the direction indicated, the flow of fluid into the fixedrectangular orifice is gradually increased until the aperture 244 ispositioned to supply a full flow of fluid to the fixed aperture 248 forachieving the peak velocity at the 135° position. During continuedclockwise rotation of the control cam 198, peak velocity is maintainedthrough the 180° and 225° positions of the workpiece change arm.

Upon movement of the control cam from the 225° to the 270° positions, itwill be apparent that the large rectangular aperture 244 is graduallymoved out of engagement with the fixed aperture 248 although theoperative alignment is maintained until the pivotal valve spool 241 ismoved into the full 270° position as schematically illustrated in G ofFIG. 6. The velocity of the workpiece change arm 112 is graduallyreduced from its peak velocity at 225° to zero velocity at 270°. At the270° position, it will be recalled that the respective workpiecescarried by the arm are moved into alignment with the retracted storagespindle 80 and workpiece operating spindle 41 as hereinbefore explained.After the interchanged workpieces have been moved into alignment withthe spindles, the spindles are moved forwardly into reengagement withthe interchanged workpieces. Subsequent to reengagement of the spindles80 and 41 with the interchanged workpieces, the workpieces are fixedlyclamped thereto by operation of the power actuated chucks 186 and 187illustrated in FIG. 7. After this has occurred, the solenoid 315 in FIG.8 is deenergized permitting resiliently biased return of the associatedvalve spool to disconnect the pressure line from the valve inlet line318 and reconnect the latter to tank, this condition being illustratedin FIG. 8. Thereupon, the valve spool 286 is resiliently returned torightward position by the spring 309, reconnecting the annular valvegroove 312 between the rectangular apertures 247, 297 and the fluidexhaust lines 314.

With this condition reestablished as illustrated in FIG. 6G, the smallaperture 243 in the valve 241 is again aligned with the fixedrectangular orifice 247 to control the rate of the workpiece change armas it is moved in a clockwise direction from the 270° position to the180° position. Return movement of the workpiece change arm 112 isschematically illustrated upon continued rotation of the velocitycontrol cam 198 in a counterclockwise direction from the 6G to 6Hpositions. The 6H position of the control cam 198 represents the peakvelocity achieved at the 225° position on return movement of the workchange arm 112 to parked position. It will be apparent that the controlcam 198 continues to rotate in a counterclockwise direction to effectleftward pivotal movement of the cam roller 238 and correspondingcontinued downward pivotal movement of the associated pivotal controlvalve 241 to gradually and completely disconnect the small fluid passingaperture 243 from the fixed rectangular valve aperture 247. With theseconditions completed, the work change arm 112 is returned to verticalparked position and the interchanged workpieces are clamped in therespective spindles 80 and 41.

Referring again to FIG. 7, it will now be assumed that the workpiecechange arm 112 is in its vertical parked position between the storageapindle 80 and the workpiece spindle 41. The tubular support frame 75for the workpiece spindle 80 has been pivoted forwardly to itshorizontal position as hereinbefore explained and as illustrated in FIG.7, and the workpiece spindle 41 has been moved axially in a manner tomove the fixture ring 102 carried thereby into axial alignment with thefixture ring 103 carried by the horizontally positioned storage spindle80. To effect such movement, the spindle 41 is rotatably journalled in aspindle headstock 31 mounted for selective horizontal movement uponhorizontal ways 32 as illustrated in FIGS. 1 and 7. To effect powerdriven longitudinal movement of the headstock 31, the recirculatingball-type antifriction nut 36 carried within the spindle headstock 31 isoperatively engaged by the rotatable screw 34. Toward its rearward end,the feed screw 34 is journalled to rotate in a bearing 328 carriedwithin the stationary machine bed 30, shown in fragmentary form in FIG.7. A gear 329 secured at the rearward end of the rotatable spindle headdrive screw 34 is engaged by an intermeshing gear 330 rotatably drivenby the motor 37. A solenoid control valve 334 is operative to connect apressure supply line to actuate the hydraulic drive motor 37 forrotating a gear 330 in selective direction to effect the requiredlongitudinal movement of the spindle headstock 31. Energization of thesolenoid 335 effects forward movement of an associated valve spool toconnect a pressure supply line for rotating a motor 37 in a direction toeffect forward movement of the spindle headstock 31. Conversely,energization of a solenoid 336 effects upward movement of the associatedspindle valve to effect reverse rotation of the motor 37 for effectingupward or rearward movement of the spindle headstock 31. With bothsolenoids 335 and 336 deenergized as illustrated in FIG. 7, theassociated valve spool is in its central neutral position to stop motorrotation and retain the spindle headstock 31 in a predeterminedhorizontal alignment with the storage spindle 80. In other words, thesolenoid controlled valve 334 is operative to selectively actuate themotor 37 for moving the spindle headstock 31 in the required directionto align the workpiece spindle 41 with the storage spindle 80.

At the start of a workpiece interchange cycle, both spindles 80 and 41are moved into positions of horizontal axial alignment. The arm 112 ispositioned in its vertical parked position between the spindles withpivot links 128 and 134 in rotatably retracted position by the linkagemechanism 123.

Solenoid 156 is energized to operate fluid actuator 130 and rod 155forwardly, thereby pivoting toggle arms 167 and 168 to maintain wedges142 and 143 retracted and compressing the actuating springs 158 and 159.

In addition, another control solenoid 354 is deenergized permittingresilient retraction of an associated valve spool 355 by a spring 356.With this condition, pressure fluid from the line 283 is transmittedthrough the upper line of the resiliently retracted valve spool 355 to ahydraulic line 359 connected to a piston actuator 360. Exhaust fluidfrom the actuator 360 is transmitted via a line 362 connected via theretracted valve spool 355 to tank. With piston actuator 360 operated asdescribed, a stop pin 361 is axially extended to positively stoprotation of the arm 112 in its 90° engaged position. Conversely,solenoid 354 is energized to retract the stop pin 366, prior toeffecting rotation of the arm 112 for interchanging workpieces.

As a last starting condition to effecting a workpiece interchangebetween the spindles, the workpiece spindle 41 is rotated into apredetermined angular position relative to the angular position of thestorage spindle 80. Doing this requires that the solenoid 176 bedeenergized to retain an associated valve spool 177 in resilientlyretracted position by spring 363. At the same time, solenoids 365 and366 are energized to extend the associated valve spools 369 and 370,thus compressing actuating springs 373 and 374. With valve spool 370extended, pressure fluid is transmitted from pressure line 283 via aline in the spool to a pressure line 375 connected to urge the pistonactuator 376 axially forward. The piston actuator 376 is carried withina nonrotatable axially movable machine member 377 that rotatablysupports the servo member 386 for axial movement; the actuator 376 isconnected via a return line 380 to exhaust via the now resilientlyretracted valve spool 177. Actuator 376 effects corresponding axialdownward movement of a flange 381 engaging an annular groove 382 in therotatable servo drive member 386. Annular clutch teeth 388 driven by theservo member 386 are moved axially forward into driving engagement withintermeshing annular clutch teeth 389 formed on an enlarged upperportion of the spindle 41.

With the actuator 381 operated to urge the clutch teeth 388 downwardinto axial engagement with driven teeth 389, a servo control valve 391carried by the member 377 is likewise moved axially downward. Asschematically shown in FIG. 7, the laterally extending actuating plungercarried by the valve is moved into the annular path of movement of astop member 392 fixedly secured to the enlarged portion of the spindle41. The servo control valve 394 is actuated to energize the associatedmotor for actuating the servo drive mechanism to effect rotation of theservo member 386 at a predetermined slow rate. With the clutch teeth 388and 389 now moved into axial engagement as described, the spindle 41 isrotated at a like slow rate until the fixture ring 102 carried therebyis moved into a predetermined angular position relative to the fixturering 103 secured to the spindle 80. The proper angular position iseffected upon annular movement of the stop 392 on the spindle 41 intopredetermined operating engagement with the now engaged servo controlvalve 391. As soon as this occurs, the valve 391 is operative via a line395 to actuate the servo control valve 394 for stopping the servomechanism 49 with the spindle 41 in its proper angular position.

With the fixture rings 102 and 103 carried by the spindles 41 and 80 inhorizontal axial alignment, a solenoid 341 is energized to effectdownward movement of an associated valve spool 342 of the motor controlvalve 282. Downward movement of the energized valve spool 342interconnects the high pressure supply line 283 via an upper valve spoolline to a motor input line 344 for effecting rotation of the motor 260in a direction to move the workpiece change arm 112 a distance of 90° ina clockwise direction into the engaged position illustrated in FIG. 7.To selectively control the rate of rotation of the motor 260 ashereinbefore explained, a rate control line 345 is interconnected via anexhaust line in the downwardly moved valve spool 342 to the commonexhaust lines 348 and 349. The controlled flow of back pressure via theline 280 operates to control the rotation rate of the motor 260 ashereinbefore explained.

At the start of a cycle, no back pressure is available to the line 280via the interconnecting line 349 and valve 287 to a line 351. This isdue to the fact that the velocity control cam 198 is angularlypositioned in such fashion as to completely disconnect both orifices 243and 244 of the pivotal control valve 241 at the start of the cycle. Toprovide the necessary back pressure to the line 280 for initiating motorrotation, therefore, the line 348 is connected via a needle valve 352 toa line 353 connected to transmit exhaust fluid pressure to the tank.Sufficient back pressure is provided to the line 280 via thepredeterminately adjusted needle valve 352 to initiate rotation of themotor 260 at the start of the cycle. As the arm member 112 begins torotate in a clockwise direction due to the interconnected needle valve352, the velocity control cam 198 begins to rotate in a manner to effectpivotal movement of the small valve 243 which is immediatelyinterconnected to supply a predetermined back pressure to the line 351for continuing rotation of the motor 260 at a gradually increasingvelocity. Rotation of the workpiece change arm 112 continues through the90° approach movement at a rate predeterminately controlled by rotationof the velocity control cam 198 effecting pivotally controlled movementof the valve 241 as hereinbefore explained.

Likewise, during the 90° approach of the arm member 112, the pivotallinks 128 and 134 carried thereby are moved into latching engagementwith the respective fixture rings 103 and 102 carried thereby, ashereinbefore described with reference to FIG. 4. Upon arrival of the armmember 112 at the 90° position, it moves into positive positionalengagement with the axially extended stop pin 366. Inasmuch as thepivotal links 128 and 134 have now been moved into positive clampingengagement with the respective fixture rings, the control system issequenced to effect deenergization of the solenoid 354 permitting thespring 356 to effect resilient retraction of the associated valve spool355. As this occurs, the line 164 is now connected to exhaust to permitresilient retraction of the fluid actuator 130. With the actuator 130deenergized, the springs 158 and 159 in the arm member 112 effect axialforward movement of the extensible wedges 142 and 143 to their outwardlylatched position, as illustrated in FIG. 7. As there shown, the wedges144 and 143 are moved outwardly into positions for locking the pivotallinks 128 and 134 into engagement with the respective fixture ringsduring the subsequent 180° pivotal interchange movement of the armmember 112.

After fixture rings 103 and 102 are fixedly clamped within the arm 112as described, solenoids 172 and 173 are energized to axially retract therods 178 and 179. As explained, axial retraction of the rods 178 and 179effects pivotal disengagement of the pivotal jaws of the chucks 186 and187 to release the spindles from the fixture rings. Then, solenoid 189is energized to move valve spool 190 to its upward position and connectlines 192 and 193 to supply fluid pressure to fluid actuators 194 and195. As schematically shown in FIG. 7, the actuators are respectivelyconnected to the upper ends of rods 397 and 398 respectively secured tothe axially movable spindle 80 and spindle headstock 31. With the chucks186 and 187 now disengaged, the fluid actuators 194 and 195 are disposedto retract the spindles 80 and 41 a distance sufficient for thedisengaged chucks to clear the respective fixture rings.

Next, solenoid 354 is energized to move valve spool 355 forward andconnect pressure line 283 to the supply line 362 connected to retractpiston 360 and the attached stop pin 361. After the stop pin 366 isretracted, the solenoid 341 is reenergized to again effect forwardmovement of the valve spool 342. Rotation of the motor 260 is againinitiated in the same clockwise direction by pressure fluid throughinput supply line 344, and controlled back pressure via line 345 and theexhaust line in the downward valve spool 342 to exhaust line 280. Theexhaust line 280 continues the controlled flow of back pressure to lines348 and 349 as hereinbefore explained with the needle valve 352connected to initiate rate controlled movement through 180°. Startingconditions for the 180° pivotal movement of the workpiece change arm 112are analogous to the movement hereinbefore described in FIG. 6. Asviewed from the rear of the machine in FIG. 6, the control cam rotatesin a counterclockwise direction from the 90° to the 270° position foreffecting the rate controlled pivotal interchange. To effectivelycontrol the rate, however, control valve 286 is actuated to connect thelarge aperture 244 in the control circuit as described in FIGS. 6 and 8.

As shown in FIG. 7, solenoid 315 is energized concomitantly with thereenergization of solenoid 341. Thereupon, the back pressure controlline 351 is connected through the large valve control orifice 244 to theline 248 and the upwardly moved diagonal valve line to the line 353.During the next 180° rotation of the work change arm 112 in a clockwisedirection, the cam 198 controls movement of the roller 238 and largevalve orifice as described in FIGS. 6, 7 and 8. During this 180°interchange movement, position control solenoid 354 is deenergized toeffect resilient retraction of the valve spool. As this takes place,pressure fluid is again transmitted by line 359 as shown in FIG. 7 toagain extend the position controlling stop pin 361.

Upon rotational advancement of the arm member through the complete ratecontrolled movement of 180°, the position of the fixture rings 103 and102 is interchanged relative to the still retracted spindles 80 and 41.In other words, the fixture ring 103 is now axially aligned with theretracted spindle 41 and the fixture ring 102 is aligned with thespindle 80. It will be apparent that this condition corresponds with thepositions described in FIG. 5D. The sequence of the control thenprovides for deenergization of solenoid 341 with resiliently biasedreturn of the valve spool 190 to its central neutral position shown inFIG. 7.

After this retracting solenoid 189 is deenergized, the spring 204 movesthe valve spool 190 forward to effect axial forward movement of theretracted spindles 80 and 41 into driving engagement with theinterchanged fixture rings 102 and 103 respectively. Reengagement isfacilitated due to the fact that the drive teeth 224 and 225 at theforward ends of the spindles 80 and 41 are positioned in predeterminedangular alignment with the intermeshing drive teeth 227 and 226 at theinner ends of the now interchanged fixture rings 102 and 103respectively.

As soon as the spindles 80 and 41 are moved forwardly into reengagementwith the interchanged fixture rings 102 and 103, solenoids 172 and 173are both deenergized to effect resiliently biased return movement of thevalve spools 174 and 175 to the positions shown in FIG. 7. Pressurefluid then flows through lines 213 and 217 to effect axial forwardmovement of the rods 178 and 179. Such movement in turn effects forwardpivotal reengagement of the power actuated chucks to securely clamp theinterchanged fixture rings to the spindles.

Since the fixture ring interchange is now completed, the solenoid 354 isreenergized to retract the stop pin 361. Likewise, another solenoid 399is energized to effect upward movement of valve spool 342 to effectmotor rotation in the opposite direction for returning the workpiecechange arm 112 to its vertical parked position. During counterclockwisereturn rotation of the change arm, pressure fluid from the line 283flows through an orifice in the now upward valve spool to the motorcontrol line 345. From the motor 260, rate control fluid is exhaustedvia the line 344 and thence through an orifice in the upward spool 342to the line 280. Rate control during return movement to parked positionis again effected by back pressure from the line 280 to the lines 348and 349 as previously explained. In this return movement, however,solenoid 315 is deenergized to effect resilient return of the valve 286to the position schematically shown in FIG. 7. Valve 286 againinterconnects the exhaust line to line 247 rendering the small orifice243 of pivotal valve 241 operative to control the rate of the arm 112 tovertical parked position.

In FIG. 9, there is shown a velocity controller 198A of modifiedconfiguration secured to a tubular control shaft 201A connected toeffect rotational control of a workpiece change arm 112 (not shown). Itwill be assumed the controller 198A is being viewed from the front ofthe machine and performs a control function analogous to the control cam198 in FIG. 7. Likewise, the cam 198A operates in a similar fashion tocontrol rotation of the shaft 201A and arm 112 through three distinctcycles of movement including a 90° approach, a 180° interchange, and a90° return to parked position in the opposite direction. As previouslyexplained in FIG. 7 the periphery of the cam 198 there shown isidentified by the numerals 1, 2, 3 and 4 extending in a clockwisedirection to relate the control effects to the three cycles of movement.The changing rates during the three cycles of movement are described inthe timing sequence control diagram in FIGS. 6A to 6G inclusive, and thevelocity control chart in FIG. 4G. As viewed from the rear of themachine in FIG. 7, the cam rotates from its "2" position in acounterclockwise direction to its "4" position to control the changingrates during a 180° cycle of interchange movement.

With the cam 198A angularly positioned as shown in FIG. 9, cam position"1A" is adjacent the cam roller 402, and cam position "4A" is adjacentthe cam roller 403. The control positions shown are those existing atthe start of a series of three control cycles; in other words with thechange arm 112 controlled by the roller 198A in its vertical parkedposition. As hereinbefore explained also, other necessary controlmovements of the arm 112 and associated parts are selectivelyinterspersed between the three cycles of rotational movement of thetubular shaft 201A as controlled by the gear 270. This arrangement isidentical to that shown and described in connection with FIG. 7.

The initial 90° approach movement is effected by a clockwise rotation ofthe cam 198A to advance the "2A" position thereof adjacent the roller402. During the next analogous 180° rotation of the shaft 201A, the cam198A is rotated an additional 180° in a clockwise direction to angularlymove the "4A" position thereof adjacent the roller 402. During 90°return movement to parked position, the cam 198A is pivoted 90° in acounterclockwise direction to move the "3A" position thereof adjacentthe cam roller 402.

Although slightly different than the arrangement described in FIG. 7,cam 198A shown in FIG. 9 is symmetrical about a vertical centerline andalso about a horizontal centerline. The two pressure compensated flowcontrol valves 406 and 407 are volume adjustment controlled by the camthrough the cam follower rollers 402 and 403. The valves 406 and 407 aredisplaced 90° relative to one another in the proper angular relationshipto the cam 198A. The fixed displacement motor 260 is connected to rotatethe shaft 201 in the proper direction to rotate the modified cam 198Asecured thereto in the proper direction. Switching the flow controlvalve 407 into and out of the hydraulic circuit is controlled by adirectional control valve 410.

The work change cycle described comprises the three distinct rotationalcycles, including the 90° approach, 180° interchange and 90° return. Asfurther explained, the three rotational cycles are each preceded andfollowed by other types of movement necessary in the workpiece changesequence. With solenoid 341A energized, the motor 260 is rotatedclockwise to effect the 90° approach movement. During this condition,fluid from the fixed displacement motor 260 is transmitted via the line345A, the leftwardly moved valve spool 342A, to the lines 351A and 290A.Fluid flow continues from line 290A and the switchable flow controlvalve 407 lines 411, 412 and thence through the valve 406 to line 414.The latter is connected to exhaust 416 which is connected to returnfluid to the hydraulic control system and supply line 283A in well-knownmanner. As the motor 260 rotates the cam 198A through the intial 90°approach, cam 198A controls the fluid flow rate through the two flowcontrol valves. Since the two flow control valves 406 and 407 areconnected in series, the valve with the smaller flow rate adjustmentwill control the hydraulic fluid. As the cam begins to rotate from its"1A" position in FIG. 9, valve 407 has a smaller flow rate adjustmentand therefore is controlling the fixed displacement hydraulic motor 260.After the cam is rotated 45° clockwise from its position shown in FIG.9, point 1A is moved into a midpoint position between the rollers 402and 403. After 45° advancement of the cam 198A, points A and B on theperiphery thereof are likewise advanced 45° to respectively engage theradially movable rollers 403 and 402. With the cam in its initial 45°clockwise position, the two flow control valves 407 and 406 are adjustedto provide the same hydraulic flow. This position of the cam 198A is atan angular displacement of 45° as shown in FIG. 9A and at an angularvelocity of "F" magnitude as shown in FIG. 9B. As the cam continues torotate in a clockwise direction to its initial 90° position, peripheralcam points "1A" and "1B" are respectively moved into positions adjacentthe cam rollers 403 and 402. As the cam 198A advances from the 45° tothe 90° position, the flow rate adjustment is less through the valve 406than through the valve 407 and therefore the valve 406 then controls thefluid flow. At this time, the angular displacement of the cam 198A isnow 90° as indicated in FIG. 9A, and the angular velocity is of "G"velocity, as indicated in FIG. 9B, very small, but greater than zero.With cam position "1A" advanced 90° to a position adjacent roller 403,the solenoid 391A is deenergized and the other workpiece changemovements effected.

The next rotational cycle is the 180° interchange movement in aclockwise direction, beginning at the 90° position of the cam 198A andterminating at the 270° position. As viewed in FIG. 9, the "2A" positionof cam 198A will be adjacent the cam roller 402. Pivotal advancement ofthe cam 198A effects pivotal advancement of the point "3A" to a positionadjacent the roller 402. To initiate the interchange, solenoid 341A isreenergized to again start clockwise movement from the 90° to the 270°position. During this condition, however, the flow control path bypassesthe flow control valve 407 in a manner that the angular velocity iscontrolled only by the flow control valve 406. This circuit is completedby energizing solenoid 415 to close valve spool 410 to complete aby-pass circuit from conductor 414 to conductor 412. As the cam 198A isrotated from 90° to 180°, the angular velocity of the cam is now at apredetermined maximum of "H" magnitude, FIG. 9A. As the cam continues torotate from the 180° to the 270° position, the hydraulic flow ratedecreases to "I" velocity, as indicated in FIG. 9A. The secondrotational cycle is then completed with the respective workpiecescarried by the arm 112 in interchanged position. Therefore, solenoid341A and solenoid 315 are deenergized since the second rotational cycleis completed.

As previously explained, other portions of the control system areactuated to insert and secure the now interchanged workpieces into thespindles. After this, solenoid 399A is energized effecting rightwardmovement of the valve spool 342A to rotate the motor 260 in acounterclockwise direction. This third rotational cycle is identical tothe first cycle, excepting that the direction of rotation is in theopposite direction. At completion of the second rotational cycle, point"4A" on cam 198A is adjacent roller 402, and point "3A" thereon isadjacent the spaced apart roller 403. From that position, the change arm112 is rotated 90° in a direction returning it to vertical parkedposition. After energizing solenoid 399A, pressure fluid flows from line283A via the rightward valve spool 342A, line 345A, moving motor 260counterclockwise, and to the return line 344A. Fluid continues via thevalve spool to lines 351A, 290A, and valve 407 to lines 411, 412 andvalve 406 to create the same rate control. Although the angulardisplacement of cam 198A is from 270° to 360°, FIG. 9A, the angularvelocity changes from "I" magnitude to a maximum of "T" magnitude andagain returns to "L" magnitude, FIG. 9B. Angular velocity of the cam198A is reduced to zero when the solenoid 399A is deenergized atcompletion of the third cycle. With the arm 112 now returned to verticalparked position between the interchanged fixture rings clamped in thespindles, cam 198A is rotatably displaced 180° from its startingposition. In other words, point "3A" of cam 198A is positioned adjacentroller 402 at the completion of the first three rotational cycles of cammovement.

From the foregoing detailed description of the illustrative structureset forth herein to disclose the principles of the present invention, itis apparent that there has been provided an improved velocity controland coordinately operative automatic latching mechanism for a machinetool transfer mechanism.

Although the illustrative embodiment of the invention has been describedin considerable detail for the purpose of fully disclosing a practicaloperative structure incorporating the invention, it is to be understoodthat the particular apparatus shown and described is intended to beillustrative only and that the various novel features of the inventionmay be incorporated in other structural forms without departing from thespirit and scope of the invention as defined in the subjoined claims.

The principles of this invention having now been fully explained inconnection with the foregoing, we hereby claim as our invention:
 1. In amachine tool having a frame;a tool operator and a work station carriedby said frame for relative movement to perform a machining operation; aloading station positioned in a predetermined spaced relationship tosaid work station for supporting workpieces to be worked upon by saidwork station and to receive completed workpieces; a rotary transfer armrotatably carried by said frame and connected to be rotated by power fortransferring the workpieces between said work station and said loadingstation; a cam connected to move with said rotary transfer arm; and arate change means actuated by said cam to regulate the rate ofacceleration and deceleration of said transfer arm during the transfermovement so that the transfer operation will be completed in minimumtime without excessively straining the associated structure.
 2. Amachine tool according to claim 1 including:a hydraulic motor connectedto rotate said transfer arm in its transfer movement; and said ratechange means comprises a hydraulic valve connected to control the flowof the pressure fluid that actuates said hydraulic motor and disposed tobe actuated by said cam for regulating the rate of rotation of saidtransfer arm.